US safety investigators called for urgent action to be taken in response to an engine issue on Boeing Co. 737 Max aircraft that can lead to smoke in the cockpit or cabin.

Safety experts recommend that the engines on Boeing’s troubled 737 Max airplanes and some Airbus models be modified quickly to prevent smoke from filling the cockpit or cabin after a safety feature is activated following a bird strike.

The National Transportation Safety Board is issuing a rare urgent safety bulletin warning of potential problems with the jet engines on Boeing 737 Max aircraft.